1. Field of the Invention
The invention relates to a keyswitch, and especially relates to a keyswitch using a spring for producing return force.
2. Description of the Prior Art
Keyswitches on the market commonly use a spring or a rubber dome for producing a required return for the keycap thereof. In general, the used spring has a single fixed spring constant. If the spring constant is small, the return force produced by the spring is small and a resistant force to a user pressing the keycap is also small, so that the user can press down the keycap quickly. However, because the return force is small, the time for the pressed keycap to return its original position is long, which is inconvenient for the user to press the keycap successively in a short time. If the spring constant is large, the return force produced by the spring is large and the pressed keycap can return its original position in a short time. However, because the return force is large, the resistant force to a user pressing the keycap is large, so that the user needs to press the keycap by a larger force, which brings a fatigue to the fingers of the user so that it is inconvenient for the user to press the keycap successively in a short time. Furthermore, the deformation mechanism of the rubber dome is different from the linear deformation of the spring. The deformation property of the rubber dome cannot be shown in a fixed spring constant. In general, at the beginning of the elastic deformation of the rubber dome, the rubber dome still can remain its geometric structure and provides a relatively large spring constant. When the structure of the rubber dome begins to buckle, the rubber dome provides a relatively small spring constant. Although the spring constant is relatively large at the beginning of the elastic deformation, the deformation amount is relatively small; although the spring constant is relatively small at the following buckling deformation, the deformation amount is relatively large. Therefore, in use, the user can sense a large threshold of pressing force, but the pressing force by the user after the threshold is small; furthermore, the whole elastic energy stored by the deformed rubber dome is not high. On the whole, compared with the keyswitch using the spring with a high spring constant, the keycap of the keyswitch using the rubber dome still takes a relative long time to return to its original position. Therefore, the current keyswitches (no matter using a spring or a rubber dome) cannot provide their keycaps an action of being pressed down quickly and returning quickly which can reduce the degree of fatigue of the fingers of the user when the user manipulates the keyswitch in some environments such as of electronic sports.